1. Field of the Invention
The present invention relates to a rear projection type display apparatus that enlarges and displays a display image on a light valve such as a liquid crystal panel.
2. Description of the Related Art
In recent years, there is known a rear projection type display apparatus reduced in thickness. The rear projection type display apparatus includes a projection unit which modulates an illumination light from a light source with a light valve to enlarge and project the modulated illumination light onto a rear surface of a screen with a projection optical system. Light rays are projected by the projection unit such that a central light ray passing through a center of an image is made incident on the rear surface of the screen at an angle other than 90 degrees through one or multiple reflection mirrors of the projection optical system.
For example, a rear projection type display apparatus as disclosed in Japanese Patent Application Laid-Open No. 2004-069776 has a structure for moving the projection unit in a depth direction with one axis of a 6-axis correction mechanism for the image, to thereby correct a projection magnification of the image.
In a case of producing the rear projection type display apparatus, the reduction in thickness is important. However, when the projection magnification is corrected by the 6-axis correction mechanism of the related art, a correction amount in the depth direction is necessary, which makes it difficult to realize the reduction in thickness.
When the projection magnification is corrected merely by moving a projection magnification correcting member having the projection unit mounted thereon, in a direction of the central light ray (substantially vertical direction) of light rays to be projected from the projection unit, it is difficult to perform the correction in a stepless manner because the projection magnification correcting member having the projection unit mounted thereon is heavy.